This site may earn affiliate commissions from the links on this page. Terms of use.

Piledriver vs. Bulldozer: Multi-core scaling

The first thing we wanted to compare was whether or not Piledriver would scale more effectively than Bulldozer in various threading scenarios. As before, we measured the performance impact of running quad-threaded tests across all four modules and eight cores (4M/8C), four modules with one core active per module (4M/4C) and two modules, with both cores active (2M/4C). We’ll start with Cinebench, a benchmark AMD points to as evidence of Piledriver’s superior performance.

Piledriver’s single-threaded performance in CB11.5 is actually a bit better than Bulldozer’s clock-for-clock, as we’ll see, but the chip still takes a significant multi-threading penalty when we run all four threads across just two modules. Microsoft’s scheduler improvements don’t do much to help here.

Maxwell Render, on the other hand, does point to some improvements between the two processors. Bulldozer’s quad-thread / octal-core render time is 8% worse than the ideal 4M/4C configuration, whereas Piledriver drops just 3% performance there. Both chips take a 20% performance hit when run in a two-module / quad-core configuration.

Next up, there’s DIEP. DIEP is a chess simulator that calculates the potential position of every piece on the board through a sequence of moves. A ply depth of one means the program has calculated every potential move a single turn into the game; a ply depth of 15 means every potential move 15 turns deep. The program spins off a pre-defined number of independent threads and uses no floating point code, which makes it useful for examining Bulldozer’s and Piledriver’s integer performance in different configurations.

Again, we see a much smaller drop off between 4M/8C and 4M/4C configurations. Good news for Piledriver on this front — now we turn to comparative performance.

Whether this graph is good news or bad depends on how much you care about single-thread performance. The good news is that the FX-8350 finally pulls unilaterally ahead of its closest Intel competitors as well as last year’s 2600K. The bad news is that a 1.06 single-threaded score at a clock speed of 4GHz is pretty terrible compared to the Core i5-3550’s 1.55x score at 3.3GHz. The X6 1100T (not pictured here), turned in an even 1.0x last year, at 3.3GHz.

Despite multi-threaded improvements, Vishera still lags the old K10 core in single-thread performance, at least in some cases.

DIEP’s performance is strictly in line with the clock speed improvement between Bulldozer and Vishera. Unfortunately.

Maxwell Render is another win for AMD, and shows a bit more than a linear performance increase. The FX-8350 is only clocked 10% faster than the FX-8150, but it finishes the render in 83% of the time. Again, it looks like AMD’s latest chip is well matched against the Core i5-3550.

One last thing we want to highlight is Piledriver’s cache performance. One of our peak concerns with Bulldozer was that the chip’s slow caches could be hampering performance. Piledriver significantly improves on this, and we suggest it accounts for a major chunk of the chip’s single-thread improvements. Keep in mind that cache latencies weren’t the only problem here — L1D latency is essentially tied to L2 latency thanks to write-through caching, and the L1 needs >2 set associativitity — but this is a start.

Power consumption was one of our main criteria that Piledriver needed to improve relative to Bulldozer — so how do things look on that front?

Power consumption is a glass half-empty (or full) sort of moment. The good news? The FX-8350 is running at 4GHz; the FX-8150 at 3.6GHz. Given that both are drawing 233W, AMD has improved the architecture’s power consumption. But, that said, the Core i5-3550 hammers the FX processors here.

Tagged In

This site may earn affiliate commissions from the links on this page. Terms of use.

ExtremeTech Newsletter

Subscribe Today to get the latest ExtremeTech news delivered right to your inbox.

Email

This newsletter may contain advertising, deals, or affiliate links. Subscribing to a newsletter indicates your consent to our
Terms of Use and
Privacy Policy. You may unsubscribe from the newsletter at any time.